Gen. Char.—Corallum composite, with an epithecate base, the corallites subpolygonal, and indissolubly united by the coalescence of their walls. The corallites are sometimes circumscribed, but they are for the most part more or less extensively connected by deficiency of their walls in particular directions, so as to give rise to sinuous rows of serially-united tubes. The calices, like the corallites, may be circumscribed, but are mostly in the form of vermiculate grooves sorresponding with the serially confluent corallites. The calices ire not oblique, nor are the corallites reclined. Mural pores are numerous and well developed. Septa and septal spines are wholly wanting. The tabulaæ are numerous, being simple and complete in the circumscribed corallites, but becoming vesicular in the rows of serially confluent corallites. New corallites are produced by fission.